1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 85Get this manual
8Point end of fuel hose into container below top of tankDepress the ball in the fuel connector until any remaining fuel is expelled9Add air to bring pressure back to 10 psi (69 kPa)10Close air release valve on adapter and remove Stevens pressure tester11Submerge fuel tank in water, one portion at time, in the same manner you would check tire for air leaksAny air bubbles indicate leak point which must be repaired or replaced12Disconnect hose from tankWith fuel connector housing submerged, check for leakage from fuel nipple and fuel valve pin (g)Depress vent valve pin to check air vent disc valve for leakage13After testing, open release valve on adapter to release tank pressure before removing cap 45C